Prototype wireless broadband devices operating in television spectrum were frequently, but not always, able to sense TV stations and wireless microphones operating in the spectrum and avoid causing interference, according to a report released late Wednesday by the U.S. Federal Communications Commission.

The report, a giant step toward allowing new wireless broadband devices to operate in unused TV spectrum, comes after several groups complained that the devices would cause interference. The National Association of Broadcasters (NAB), some mobile-telephone carriers and wireless-microphone vendors have opposed the request by several large tech vendors to allow new wireless devices to operate in unoccupied TV channels.

However, the report also noted that some prototype devices had difficulty finding wireless-microphone signals operating in the TV spectrum during a series of tests conducted over the past year. The debate is likely to continue as the FCC moves forward with its effort to allow devices such as new smartphones to use the so-called white spaces of the television spectrum.

The National Football League, the ESPN network and several lawmakers and churches have also raised concerns about potential interference by new devices in the white spaces. Both sides in the debate have conducted intense lobbying campaigns in recent months.

Tech vendors cheered the FCC report. It is "great news" for tech vendors looking to provide a new avenue for customers to connect to broadband, said Steve Sharkey, Motorola's senior director of regulatory and spectrum policy.

The report came out just hours after FCC Chairman Kevin Martin told reporters that he'd support the use of new broadband devices in the spectrum white spaces. The FCC is scheduled to vote on an order to move the white-spaces plan forward during its Nov. 4 meeting, Martin said.

The report "sets the stage for the FCC to move forward," Sharkey said. "This really shows the commission is taking the issue seriously."

Representatives of the NAB and microphone maker Shure weren't immediately available for comment.

For more than two years, large tech companies and consumer groups have been pushing for the FCC to approve use of the spectrum white spaces. Among the companies and groups calling for the FCC to approve white-space devices are Microsoft, Google, Dell, Hewlett-Packard, Public Knowledge, Free Press and the VON Coalition.

FCC approval of the devices would spur innovation and create new jobs in the tech sector, and allow consumers to have a new option for broadband service, supporters say. The TV spectrum would allow broadband signals to travel significantly farther than the spectrum used by WiFi.

But TV stations and wireless-microphone vendors raised concerns about interference even as the FCC conducted tests on prototype devices. The NAB said the FCC tests gave no proof that their signals would be protected from interference. Wireless microphones have long operated in the TV spectrum without FCC licenses, and microphone vendors raised many of the same concerns as TV stations.

During FCC tests, a handful of prototype devices failed, but they generally stopped working for various reasons and didn't cause interference.

Microsoft applauded the FCC's report. "We urge the commissioners to come to a decision quickly and adopt rules that will allow all Americans to realize the full and enormous potential white spaces have to expand broadband access in underserved, urban, and rural areas and to enable a new wave of innovation and Internet services and products," Anoop Gupta, Microsoft's corporate vice president for technology policy and strategy, said in a statement.

All five devices submitted to the FCC for a second round of testing, starting in October, "were able to reliably detect the presence" of a clean digital television signal, the FCC report said. The detection sensitivity varied considerably, however, the report said.

The report noted other problems as well. The devices often had difficulty sensing TV signals in adjacent channels. "This could impact significantly the ability of the devices to reliably detect TV signals within stations' service areas," the report said.

The FCC tested for wireless-microphone interference in a laboratory and in field tests. It tested three devices for interference with wireless microphones during field tests at a professional football game in Maryland and a Broadway play in New York. While the devices were able to detect wireless-microphone signals when no other signals were present, the "detection threshold sensitivity of all of the devices was severely impacted" when a TV signal was nearby, the report said.

A prototype device from Philips indicated that channels were occupied even when they weren't, and a device from the Institute for Infocomm Research "indicated several channels as available even when the microphones were on," the report said.

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